mail-unquote

Remove quoting from the current quoted section.

Ctrl-C <

This command removes email-style quoting. It examines the lines
around point to find a range of lines with matching quoting, then
removes the quoting (by default, > or # characters) from those
lines. If a region has been highlighted, it removes quoting only from
those lines. It uses the mail-quote-pattern
and mail-quote-skip variables to determine the
permissible quoting characters.